Global Climate Change: Impacts, Causes, and Solutions - Prof. John T. Coates, Study notes of Environmental Science

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Chapter 21 – Global Climate Change Introduction to Climate Change  Earth’s temperature is based on daily measurements at several thousand land-based meteorological stations around the world  Phenologicial spring – determine by when buds of specific plants open, and autumn by when leaves of specific trees turn color and fall o spring comes about six days earlier and autumn about five days later  heat stress events o very hot, humid days and nights during summer months  rate of sea-level rise has increased  IPCC concluded that human-produced air pollutants have caused most of the climate warming observed over the last 50 years  Emissions scenario – a prediction about the amounts, rates, and mix of future greenhouse gases  Greenhouse gases – gases that absorb radiated heat from the sun o CO2, methane (CH4), nitrous oxide (N2O), CFCs and tropospheric ozone (O3) o Increase the temperature of the atmosphere  Human contribution to total carbon dioxide – the burning carbon-containing fossil fuels – coal, oil, and natural gas  Gases absorb infrared radiation – radiated heat from the sun  Radiative forcing – the capacity of a gas to affect the balance of energy that enters and leaves Earth’s atmosphere  Greenhouse effect – the natural trapping of heat in the atmosphere o Gases that absorb infrared radiation are called greenhouse gases o Enhanced greenhouse effect – greenhouse gases accumulating in the atmosphere as a result of human activities  Positive feedback – a situation in which a change in some condition triggers a response that intensifies the changed condition o Water vapor  Aerosol effect – atmospheric cooling that occurs where and when aerosol pollution is the greatest o Very tiny particles that remain in the troposphere for extended periods of time  Sulfate-laden haze tends to cool the planet by reflecting some of the incoming sunlight back into space, away from Earth o Comes mainly from the stacks of the same power plants mostly responsible for the CO2 emissions  Increased concentrations of some greenhouse gases will persist in the atmosphere for years to hundreds of years  Whereas human-produced sulfur emissions remain for only days, weeks, or months  Complex climate system o Winds, clouds, ocean currents, albedo  Each exert its influence on the climate  Models developed because interactions are too large and complex to contrast a testing laboratory o Used to explore and analyze past climate events, and project future warming and suggest consequences of warming on the biosphere and its life-support systems  Unpredictable and extreme climate change o Disruption of the ocean conveyor belt – transports heat around the globe o Models show an abrupt climate change could occur o Climate warming and freshwater melting off the Greenland ice sheet, could weaken or even shut down the ocean conveyor belt  Could cause major cooling in Europe  Would not sequester as much carbon in the ocean – leading to a positive feedback loop  Less CO2 in the ocean leads to more CO2 in the atmosphere, which would lead to greater atmospheric warming causing the ocean belt to weaken further The Effects of Global Climate Change  Sea level rise of 18 to 59cm by 2100. o Two factors: o Water expands as it warms  Thermal expansion o Water absorbs more heat than does ice, which is highly reflective o Melting ice has a positive feedback effect on heating: water absorbs more heat, which causes more ice to melt  The area of ice-covered ocean in the Arctic has decreased significantly over the past several decades  Mountain glaciers also melting at accelerating rates contributing so sea-level rise  Precipitation patterns o Causing some areas to have more frequent droughts o Heavier snow and rainstorms are projected to cause more frequent flooding in other areas o Affect availability and quality of fresh water in many locations o Predictions of greater extremes of drying and heavy rainfall during El Nino event  Coral reefs – impacted by climate changes in two ways o Acidification o Temperature increases  Temperature related coral bleaching – occurs when water temperature exceeds a threshold, affecting the coral symbiotes and making them and the corals more susceptible to disease-causing organisms that healthy corals are normally resistant to o Increased acidity exacerbates this effect  Dissolved organic compounds – absorb UV penetration  Acid deposition affects the amount of dissolved organic compounds in a lake Dealing with Global Climate Change  Mitigation – focuses on limiting greenhouse gas emissions to moderate or postpone global climate change, thus buying time to pursue solutions that stop or reverse the change  Adaptation – focuses on learning to live with the environmental changes and societal consequences brought about by global climate change  Carbon management – ways to capture and store CO2  Carbon Capture and Storage (CCS) – also called carbon sequestration  Most pressing issue is rising sea level  International community recognizes that it must stabilize CO2 emissions  UNFCCC – goal was to stabilize greenhouse gas concentrations in the atmosphere at levels low enough to prevent dangerous human influences on the climate  Kyoto Protocol – international treaty, legally binding, provides operational rules on reducing greenhouse gas emissions  EPA developing policies in response to a Supreme Court decision that requires the EPA manage CO2 as an air pollutant  Explain radiative forcing, greenhouse gases, and the enhanced greenhouse effect o Radiative forcing is the capacity of a gas to affect the balance of energy that enters and leaves the atmosphere. Greenhouse gases are the gases in Earth’s atmosphere that absorb infrared radiation. The enhanced greenhouse effect is the additional warming produced by increased levels of gases that absorb infrared radiation (heat). The Intergovernmental Panel on Climate Change concluded in 2007 that human-produced greenhouse gases are the most likely cause of recent climate warming and that the world will almost certainly warm substantially during the 21st century  Explain how climate models project future climate conditions o Climate models are computer models that describe the global climate as a system. The models divide the atmosphere and oceans into small, three-dimensional parts and evaluate the effects of change in one part on adjacent parts. These models incorporate positive and negative feedbacks that influence such factors as temperature, wind patterns, cloud moisture, and ice cover. Running these models based on different predicted levels of CO2 leads to projections of possible future climate conditions. Models include positive feedback, in which